i would start with getting out my owners manual & reading the 'maintenance/cleaning' section- go through the process step by step- when we don't do it regularly it's easy to forget a step or two- then i would go to the 'trouble shooting' section of the manual & read through the specific issues- what to do-
if all that does not work then it's time for a service call....and do you change your needle often? sometimes something as simple as that can make a huge difference